Why is the louver box placed on the open lawn 1.5 meters above the ground?

The highest temperature of weather station is the air flowing temperature in natural state, which is the standard temperature. It is measured with shutters. The shutter box is placed on the lawn, which is not affected by direct sunlight, wind, rain and natural ventilation. The thermometer is placed in a louver and measured at 1.5 meters above the ground. This is the standard set by the World Meteorological Organization. It represents the undisturbed standard air temperature in the natural state. Usually, the temperature in the weather forecast represents the temperature in nature.